runaway slaves and other fugitives. The Rio Grande valley in South Texas was home to a large palm tree forest when Spaniards first arrived, though today very little of it remains. The development of railroads in the eastern part of the state during the mid-19th century led to a boom in lumber production in the 1880s. This era of financial success lasted approximately 50 years finally coming to an end as Texas's forests were decimated and the Great Depression dropped prices. In 1901 the Gladys City Oil, Gas, and Manufacturing Company struck oil on Spindletop Hill in Beaumont. Though petroleum production was not new, this strike was by far the largest the world had ever seen. The find led to widespread exploration throughout Texas and neighboring states. By 1940 Texas was firmly established as the leading oil producer in the U.S. Texas remained largely rural until World War II though the success of the petroleum industry rapidly expanded the economy with heavy industry of many types taking root. The second world war created tremendous demand for petroleum and a variety of products that Texas was in a unique position to provide. By the end of the war Texas was one of the leading industrial states and the population had become predominantly urban. Additionally the economy had diversified sufficiently that, though petroleum was still the largest sector by the end of the war, the business community in the state was truly diverse. The Texas economy today relies largely on information technology, oil and natural gas, aerospace, defense, biomedical research, fuel processing, electric power, agriculture, and manufacturing. Exports In 2014, for the thirteenth year in a row, Texas led the United States in export revenues. Texas exports for 2008 totaled $192.2 billion. In 2002, the Port of Houston was 6th among the top sea ports in the world in terms of total cargo volume; Air Cargo World rated Dallas/Fort Worth International Airport as "the best air cargo airport in the world". The ship channel at the Port of Houston—the largest in the U.S. in international commerce and the sixth-largest port in the world. Taxes According to the Tax Foundation, Texans' state and local tax burdens are among the lowest in the nation, 7th lowest nationally, with state and local taxes costing $3,580 per capita, or 8.7% of resident incomes. Texas is one of only 7 states not to have a state income